Polyester packaging material

ABSTRACT

White goniochromatic packaging article. The package wall containing a composition useful for blocking light in the spectrum ranges from about 200 nm to about 1200 nm. The composition has polyester, polymethylpentene, and a light scattering pigment. The composition optionally includes at least one other colorant. Each of the polymethylpentene and the light scattering pigment comprise about 0.1 to about 0.5 weight percent of the wall. The polyester and polymethylpentene are immiscible and when subjected to orientation stresses the composition produces a goniochromatic packaging article.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority and benefit of U.S. ProvisionalPatent Application Ser. No. 62/611,713, entitled “White PolyesterPackaging Material” filed on Dec. 29, 2017. This application also claimsthe priority and benefit of U.S. Provisional Patent Application Ser. No.62/764,783, entitled “White Polyester Packaging Material” filed on Aug.16, 2018. Each application is incorporated herein by reference in theirentireties.

FIELD

The present invention relates to packaging. In particular, the inventionrelates to packaging with a high lightness value, high light blocking, alow percentage of additives, and a goniochromatic appearance (uniformcolor across all viewing angles).

BACKGROUND

In the field of packaging, plastic has taken the place of othermaterials such as glass. This substitution minimizes breakage, reducesweight, and reduces energy consumed in manufacturing and transport.

Attracting consumers to purchase individually-sized or family-sizedcontainers includes branding and trade dress. Among the elements ofvaluable trade dress is the color of the container. Among the elementsof valuable branding is consistent visibility of color. For certainproducts, such as milk, a light or bright white container is desired.

Lightness can be defined within the CIELAB color space, whichmathematically describes all perceivable colors in three dimensions: L*for lightness, a* for green-red, and b* for blue-yellow. FIG. 1 depictsthe CIELAB color scale. In the CIELAB color space, the L* axis runs fromtop to bottom. The maximum for L* is 100, which would be a perfectreflecting diffuser (i.e., the brightest white). The minimum for L*would be 0 which would be a perfect absorber (i.e., the darkest black).Positive a* is red. Negative a* is green. Positive b* is yellow.Negative b* is blue.

One of the most important attributes of the CIELAB model is deviceindependence. This means that the colors are defined independent oftheir nature of creation or the device they are displayed on. TheL*-value of the CIELAB color scale can be obtained using any CIELABcolor measurement instrument and is calculated using the formula:

$L^{*} = {{116 \cdot \sqrt[3]{\frac{Y}{Y_{n}}}} - 16}$

Wherein Y is the CIE tristimulus value and Y_(n) is the tristimulusvalue for the illuminant. The CIELAB model permits the quantification ofhow light a product actually is. Lightness is typically achieved byadding highly reflective and minimally absorbing components, for exampletitanium dioxide (TiO₂).

Goniochromatic packages maintain color and appearance across all viewingangles. Goniochromatic packages are beneficial for uniform colorconsistency and brand recognition regardless of the viewing position ofa consumer. Conversely, gonioapparent packages show a color differenceacross viewing angles. Metallic or pearlescent effects aregonioapparent. While metallic or pearlescent effects can be eyecatching, they can lead to reduced brand recognition and colornon-uniformity.

Phase-separated mixtures, as depicted in FIG. 3, result when one mixesimmiscible polymers. However, when these phase-separate mixtures aresubjected to orientation stress (e.g., blow molding, biaxial sheetorientation, monoaxial stretching, thermoforming, or fiber spinning),the spheres of the minor immiscible component flatten. The problem issuch immiscible components may not entirely flatten leading to internaloverlapping voids within the structural polymer, as depicted in FIG. 4.These voids create a multitude of light scattering surfaces that reflectlight in a non-uniform manner resulting in a gonioapparent effect (i.e.pearlescent or metallic appearance) where the color difference acrossviewing angles changes by more than 10 units DE_(CMC).

Gonioappearance can be measured with a multi-angle spectrophotometer,such as an MA-T12 from X-Rite. ASTM E2175 describes the standardpractice for specifying the geometry of multi-angle spectrophotometers.The color difference, as calculated using CIELAB DE_(CMC), between nearspecular and far-specular viewing angles can be used to quantify themagnitude of the gonioappearance. Using a 45° incident light source andmeasuring color at near-specular) (15°) and at far specular (110°), thecolor difference demonstrates the change in appearance over a range ofviewing angles. FIG. 2 shows such a measurement for gonioappearance. Forsuch a measurement a difference of more than 10 units DE_(CMC) issignificant and indicates gonioappearance. A difference of less than 10units DE_(CMC) is not significant and indicates a goniochromaticappearance.

Light barrier is also desired because there is a need to obscure thecontent of a package or to prevent quality degradation of the packagedproduct during the period of time between packaging and consumption.Light exposure can cause undesired changes to packaged goods. Preventingthis degradation is difficult to accomplish when the product issensitive to light radiation. In milk, for example, light has bothdeleterious photochemical and ionizing effects. Specifically, riboflavinphoto-degrades when exposed to light between 200 nm and 520 nm. Thisdegradation deleteriously affects the taste and odor of the milk.

A light barrier restricts certain wavelengths of light from passingthrough package walls. This can be achieved through reflection orabsorption, which prevents deleterious effects to the contents heldwithin the package. However, typical methods to achieve light barrierare associated with trade-offs in performance in other critical areas ofthe package.

A bright white color would reflect almost all light, thereby protectingthe product from further degradation. Previously, to obtain a brightwhite container packagers would add colorants or opacifiers. Suchadditional colorants or opacifiers increased the cost of the containerand can result in a swirled appearance (i.e., the colorant and/oropacifier would not appear to have fully dispersed within thecomposition), which may have a negative impact on the consumer'sperception of the product. Opacifiers may also lead to reduced physicalproperties due to high pigment content, reduced ability to recycle, andlower gloss. For PET blow molded bottles or thermoformed parts, highlevels of opacifiers leads to difficulty reheating preforms due to thehigh reflectivity of infrared light.

To overcome high reflectivity, absorbing pigments and/or dyes arecommonly used to increase light barrier and reduce the total colorantcontent. However, adding absorbing pigments also reduces the lightnessof a package. Creating a lighter package with high light barrier has, todate, required sacrificing either lightness, light barrier, or highloading levels (affecting cost, physical properties, gloss,recyclability).

U.S. Pat. No. 4,377,616 describes lustrous satin appearing, opaque filmcompositions and method of preparing same. U.S. Pat. No. 5,089,309describes a semitransparent resin container with pearly luster. U.S.Pat. No. 4,368,295 describes films from compositions of polyesters andolefin polymers. U.S. Pat. No. 3,640,944 describes modified polyesterfilm for punched tapes. U.S. Pat. No. 8,575,296 describes polyesterarticles having simulated metallic or pearlescent appearance. EP2035209B1 discloses a preform and container for radiosensitive productsand method for manufacture thereof. U.S. Publication No. 2017/0306143A1discloses a light barrier composition and articles comprising same.

The references identified above all disclose articles with a pearlescentappearance, also described as lustrous, nacreous, or metallic, which isnot desirable. Furthermore, these references evidence that the use ofincompatible polymers such as polypropylene must be used at high loadinglevels greater than 5% and do not have a synergistic effect when used incombination with a light scattering pigment. In summary, such referencesdo not disclose how to create a goniochromatic appearance with aconstant color across a wide range of viewing angles and synergisticallyimproves light barrier, by allowing for a reduced loading of additives,higher L*, and a brighter, whiter appearance with low loading levels ofincompatible polymers.

Thus, there is a need for a low cost, goniochromatic compositionproduced from immiscible polymers. It is desirable that the compositionhave anti-swirl behavior that provides whiteness and lightness withoutthe typical trade-offs in light barrier, or any other properties such asphysical properties, recyclability, gloss or ability to reheat.

SUMMARY

White articles made with phase separated materials are known to have anacreous or pearlescent effect (i.e., a gonioapparent appearance). Ithas been discovered that using polymethylpentene and a light scatteringpigment has an unexpected synergistic effect, even at very low additionlevels for such components and creates a package wall with agoniochromatic appearance and excellent light blocking properties.

Such a wall includes a polyester combined with an orientedpolymethylpentene and a light scattering pigment. About 0.1 to about 5.0percent of the weight of the wall is polymethylpentene and about 0.1 toabout 5.0 percent of the weight of the wall is a light scatteringpigment. The ratio of polymethylpentene to light scattering pigment inthe wall is from about 5:1 to about 1:5. Furthermore, the wall isgoniochromatic.

Combining a light scattering pigment with polymethylpentenesynergistically increases light reflection, which consequently enhancesthe light barrier. Since the synergistic increase in light reflectiondoes not occur until after orientation (e.g., blow molding), the L* andwhiteness index may be lower prior to orientation. Because of thereduced amount of colorants and/or opacifiers, the composition exhibitsanti-swirl behavior as a lower concentration may be easier to disperse.As a result, the disclosed composition provides a low cost compositionwith anti-swirl behavior that requires little to no opacifiers orcolorants to produce a bright white goniochromatic package.

Without a light scattering pigment, a package with elongated plate-likelight scattering surfaces will have a gonioapparent appearance, showinga large color change across a range of viewing angles and may beunrecognizable depending on the lighting conditions and viewer position.Adding a light scattering pigment to the structural polymer (e.g.,polyester) and polymethylpentene composition surprisingly eliminates thegonioappearance with just a small amount of a light scattering pigment,as low as 0.1%.

In certain embodiments of the invention, the light scattering pigment isselected from the group consisting of aluminum trihydrate (Al(OH)₃),titanium dioxide (TiO₂), barium sulfate (BaSO₄), zinc sulfide (ZnS),mica, ultramarine blue (PB 29), metal oxide particles such as pigmentyellow 53 (PY 53), red iron oxide (PR 101), black iron oxide (PBlk 11),Chromium Green-Black Hematite (PG 17), cobalt aluminate (PB 28), andcombinations thereof.

Another effect of the reduced amount of pigments or colorants is betterphysical properties. Colorants and/or opacifiers can contribute topolymer degradation by bringing moisture and increasing shear stress inpolymer processing. Additives also reduce the total amount of structuralpolymer that can contribute to physical properties. Degraded polymer canresult in decreased physical properties such as top load, tensilestrength, or environmental stress cracking.

Another effect of the reduced amount of colorants and/or opacifiers isimproved reheat performance. Colorants and/or opacifiers that typicallyemployed to create white packages reflect light, including IR lightoften used to reheat packaging materials for thermoforming or bottleblowing. With less IR reflected light, a structural polymer will absorbmore efficiently and reheat more uniformly. Since polymethylpentenecreates reflection after orientation, the color and appearance of anoriented sample will be different than a non-oriented (i.e., amorphous)sample.

Another effect of the reduced amount of colorants and/or opacifiers isimproved or maintained gloss. Colorants and opacifiers can impactsurface smoothness when used at very high loadings, resulting in a lessglossy appearance. Reducing the amount of colorants maintains surfacesmoothness and a highly glossy appearance.

Another effect of the reduced amount of colorants and/or opacifiers isimproved recyclability. Colorants and/or opacifiers can be consideredcontaminants in the recycle stream. Since the polymethylpentene does notshow strong reflectivity until after orientation, recycling into anon-oriented article has less impact on the recyclability than otherpigments and/or colorants.

In certain embodiments of the present invention, the package wall maycontain a second pigment or a colorant, separate from the lightscattering pigment, wherein the second pigment is selected from thegroup consisting of: dyes, pigments, thermochromic pigments, fluorescentpigments, pearlescent pigments, and metallic pigments, or a combinationthereof.

In certain embodiments of the present invention, the gonioappearance ofthe wall is less than 10 units, measured as DE_(CMC) with a 45° incidentlight source between 15° near-specular reflection and 110° far specularreflection.

In certain embodiments of the present invention, the polyester isselected from the group consisting of: polyethylene terephthalate (PET),copolymers of PET, polybutylene terephthalate (PBT), copolymers of PBT,polylactic acid (PLA), poly trimethylene terephthalate (PTT),polyethylene naphthalate (PEN), polyethlene furanoate (PEF),polycyclohexylene dimethylene terephthate (PCT), copolymers of PCT,sulfonated polyesters, copolymers of polyesters, polycaprolactone (PCL),polyhydroxyalkanoate (PHA), and copolymers of PHA.

In certain embodiments of the present invention, polymethylpentene makesup: about 0.1 to about 3.0, about 0.2 to about 2.0, or about 0.2 toabout 4.0 percent of the weight of the wall.

In certain embodiments of the present invention, the ratio ofpolymethylpentene to light scattering pigment in the package wall isfrom: about 4:1 to about 1:4, or about 3:1 to about 1:3.

In certain embodiments of the present invention, the light scatteringpigment is titanium dioxide (TiO₂).

In certain embodiments of the present invention, the wall has a lightbarrier for light with wavelengths ranging from about 200 nm to about1200 nm of greater than: about 90, about 95, about 98, about 99, orabout 99.5 percent. In other embodiments, the wall has a light barrierfor light with wavelengths ranging from about 400 nm to about 700 nm, ofgreater than: about 90, about 95, about 98, about 99, or about 99.5percent

In certain embodiments of the present invention the L* value of the wallaccording to CIELAB color space is greater than: about 75, about 80, orabout 85.

In certain embodiments of the present invention, the wall is amono-layer container wall. In other embodiments the wall is amulti-layer container wall wherein at least one layer includes apolyester an oriented polymethylpentene and a light scattering pigment.

In certain embodiments, additional (i.e., a separate component from thelight-scattering pigment) colorants are added to the wall including:dyes, special effects pigments, or other additives such as UV absorbers,anti-oxidant stabilizers, dispersants, waxes, slip additives, otherpolymers, or other components such as, for example, thermochromicpigments, fluorescent pigments, pearlescent pigments, and metallicpigments.

In certain embodiments of the present invention, the polymethylpenteneis oriented by injection stretch blow molding, extrusion blow molding,film or sheet uniaxial or biaxial orientation, blown film, thermoformingor fiber spinning. There are no specific limits on orientation. Ingeneral, higher orientation leads to higher reflecting surfaces andhigher light blocking.

Finally, a method of producing the package wall is disclosed whereby apolyester, a polymethylpentene, and a light scattering pigment arecombined to produce a mixture having about 0.1 to about 5.0 weightpercent of polymethylpentene and about 0.1 to about 5.0 weight percentof the light scattering pigment. Furthermore, the ratio ofpolymethylpentene to light scattering pigment is from about 5:1 to about1:5. The wall is then produced by subjecting the mixture to orientationstress thereby orienting the structural polymer.

In certain embodiments, the density of the mixture prior to beingsubject to the orientation stress is equal to or lower than that of thepolyester. In other embodiments, the density of the wall after beingsubject to the orientation stress is equal to or lower than that of thepolyester.

In a non-limiting embodiment, a product may added to a container withwalls having an oriented polyester, polymethylpentene, and a lightscattering pigment and optionally another pigment and/or a colorant. Thecontainer may then be sealed.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, but are notrestrictive, of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of the CIELAB L*, a*, b* color space;

FIG. 2 is a diagram of gonioapparent color measurement.

FIG. 3 is an exemplary embodiment of a mixture of immiscible polymers;and

FIG. 4 is an exemplary embodiment of a mixture of immiscible polymerssubject to orientation.

DETAILED DESCRIPTION

Embodiments disclosed herein include compositions that are useful in themanufacture of bright white packaging. Embodiments include a packagewall comprising, consisting essentially of, or consisting of: apolyester; from about 0.1 to about 5.0 weight percent polymethylpentene;and from about 0.1 to about 5.0 weight percent light scattering pigment,wherein the ratio of polymethylpentene to light scattering pigment isfrom about 5:1 to about 1:5, and the wall is goniochromatic. Oncesubject to biaxial orientation stress (e.g., blow molding) the packagewall is bright white, having an L*-value according to the CIELAB colorscale of greater than about 75. Furthermore, in some embodiments, thecomposition has a light barrier of greater than 90 percent for lightwithin the wavelength of between about 200 nm to about 1200 nm.

Polyester Structural Polymer

As used herein, the term “structural polymer” refers to a polymericmaterial comprising a majority of the composition and which provides themajority of the mechanical properties to an article such as, forexample, a plastic container. Preferably, the structural polymer is apolyester polymer. The structural polymer is referred to as referenceNo. 100 in FIGS. 3 and 4.

Any polyester is a candidate for use in the present invention. Theformation of a polyester from a monool or a polyol and an acid or itsester encompasses many different suitable types of polyesters for use inthis invention. The monomeric units can be formed reactions of eitheraliphatic moieties, aromatic moieties, or both. Desirably, the polyesteris transparent or semi-transparent.

Non-limiting examples of polyesters include terephthalates,terephthalate glycols, lactides, (hydroxy)alkanoates, copolyesters ofterephthalic acid residues, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and1,4-cyclohexanedimethanol, etc., or combinations thereof.

Additionally, one can use homopolyesters or copolyesters, such ashomopolymers and copolymers of terephthalic acid and isophthalic acid.The linear polyesters may be produced by condensing one or moredicarboxylic acids or a lower alkyl diester thereof, e.g.,dimethylterephthalate, terephthalic acid, isophthalic acid, phthalicacid, 2,5-, 2,6-, or 2,7-naphthalene dicarboxylic acid, succinic acid,sebacic acid, adipic acid, azelaic acid, bibenzoic acid andhexahydroterephthalic acid, or bis-p-carboxyphenoxyethane, with one ormore glycols, e.g., ethylene glycol, pentyl glycol, and1,4-cyclohexanedimethanol.

Of these various polyester candidates, because of commercialavailability, the terephthalates, such as polyethylene terephthalate(PET) or polybutylene terephthalate (PBT), the lactides, such aspolylactic acid (PLA), and the hydroxyalkanoates, such aspolyhydroxybutyrate (PHB) or polyhydroxybutyrate-co-valerate (PHBV), aredesirable for use. PET is preferred because of its ubiquity and cost,although PLA and PHBV are emerging as bio-derived thermoplasticpolyesters which can supplant PET in some situations. In someembodiments, PET may be blended with other polyesters.

Polymethylpentene

As used herein “polymethylpentene” refers to a thermoplastic homopolymeror copolymer consisting primarily of 4-methyl-1-pentene units.Polymethylpentene may include copolymers with 1-decene, 1-hexadecene,1-octadecene, or combinations thereof. Referring to FIGS. 3 and 4,polymethylpentene is referred to as reference No. 110 and isincompatible with the polyester structural polymer 100 and constitutes aminor, dispersed phase. In a non-limiting embodiment, polymethylpentene110 is present at from about 0.1 weight percent and about 5.0 weightpercent of the composition.

When present in a wall for a package, polymethylpentene 110 is presentat from about 0.1 weight percent and about 5.0 weight percent, or fromabout 0.1 to about 3.0 weight percent, or from about 0.2 to about 2.0weight percent, or from about 0.2 to about 4.0 weight percent, or fromabout 0.1 to about 0.5 weight percent, or from about 0.1 to about 0.7weight percent, or from about 0.1 to about 1.0 weight percent, or fromabout 0.5 to about 2.0 weight percent, of the weight of the wall.

With reference to FIGS. 3 and 4 and without being bound by anyparticular theory, it is believed that when a structural polymer 100with a dispersed phases of polymethylpentene 110 is subjected toorienting stress (e.g., blow molding), the rigidity and surface tensionof the polymethylpentene 110 allows the structural polymer 100 to flowaround the polymethylpentene 110. Polymethylpentene 110 maintains itsshape, within a reasonable degree of tolerance, resulting in theformation of voids 120 within the structural polymer 100. Lightscattering pigments, disperse within the structural polymer 100, eventhough they may have at one time been dispersed in polymethylpentene110. The light scattering pigments scatter light over a range ofdirections and disrupt the gonioapparent appearance from the voids 120to create a goniochromatic appearance. Thus, polymethylpentene 110, whencombined with light scattering pigments in a composition employed toform a container by an orientation process (e.g., blow molding) impartsa goniochromatic appearance to a container wall once oriented.

In some embodiments, compositions and package walls disclosed herein arefree of polypropylene.

Light Scattering Pigment

As used herein “light scattering pigment” refers to any inclusion withinthe structural polymer 100 or within the immiscible polymer thatinteracts with incident light by primarily diffracting light andoptionally scattering and/or absorbing. Diffraction occurs as a resultof a difference in refractive index between the light scattering pigmentand the immiscible polymer or the structural polymer 100. Lightscattering pigments may solely diffract, as in the case of titaniumdioxide (TiO₂), or they may both scatter and absorb, as in the case ofblack iron oxide (PBlk 11). Some examples of light scattering pigmentsinclude titanium dioxide (TiO₂), ultramarine blue (PB 29), metal oxideparticles such as red iron oxide (PR 101), black iron oxide (PBlk 11),chromium green-black hematite (PG 17), or cobalt aluminate (PB 28),aluminum trihydrate (Al(OH)₃), barium sulfate (BaSO₄), zinc sulfide(ZnS), or mica.

When present in a wall for a package, light scattering pigment ispresent at from about 0.1 weight percent and about 5.0 weight percent,or from about 0.1 weight percent and about 4.0 weight percent or fromabout 0.1 to about 3.0 weight percent, or from about 0.2 to about 2.0weight percent, or from about 0.2 to about 4.0 weight percent, or fromabout 0.1 to about 0.5 weight percent, or from about 0.1 to about 0.7weight percent, or from about 0.1 to about 1.0 weight percent, or fromabout 0.5 to about 2.0 weight percent, of the weight of the wall.

Furthermore, the ratio of polymethylpentene to light scattering pigmentby weight of the wall is from about 5:1 to about 1:5, or from about 4:1to about 1:4, or from about 3:1 to about 1:3, or from about 2.5:1 toabout 1:2.5, or from about 2:1 to about 1:2, or from about 1.5:1 toabout 1:1.5, or from about 1.25:1 to about 1:1.25, or from about 0.75:1to about 3:1, or from about 0.5:1 to about 3:1, from about 0.75:1 toabout 2:1, or from about 0.5:1 to about 2:1.

Gonioappearance

Gonioappearance of a surface 200 can be measured with a multi-anglespectrophotometer, such as an MA-T12 from X-Rite. The color differencefrom an original light source 210, as calculated using CIELAB DECMC,between an initial specular viewing angle 220, a near-specular viewingangle 230, and a far-specular viewing angle 240 may be used to quantifythe magnitude of the gonioappearance. The original light source 210 mayapproach the surface 200 at any desired angle. For example, as depictedin FIG. 2, the light source 210 may approach the surface at about a 45degrees angle of incidence. Furthermore, the near specular viewing angle230 forms an angle with the initial specular viewing angle 220 that isless than the angle formed by the far specular viewing angle 240 and theinitial specular viewing angle 220. For example, as depicted in FIG. 2,the near specular viewing angle 230 may be 15 degrees and the farspecular viewing angle 240 may be 110 degrees.

Colorant

The instant compositions optionally includes at least one colorant. Thecolorant may absorb a first range of light wavelengths, contained withina spectrum of light wavelengths between about 200 nm and about 1200 nm.Suitable colorants include any of the organic dyes, organic pigments,inorganic dyes and inorganic pigments that are typically used ascolorants in polymer applications. Examples of such colorants includethe following colorants of respective colors to be shown below. In thefollowing, the designation “C. I.” means color index.

A black colorant includes, for example, carbon black, copper oxide,manganese dioxide, aniline black, activated carbon, non-magneticferrite, magnetic ferrite, and magnetite.

A yellow pigment includes, for example, C.I. pigment yellow 13, C. I.pigment yellow 14, C. I. pigment yellow 17, C. I. pigment yellow 74, C.I. pigment yellow 93, C. I. pigment yellow 155, C. I. pigment yellow180, and C. I. pigment yellow 185.

An orange colorant includes, for example, red chrome yellow, molybdenumorange, permanent orange GTR, pyrazolone orange, vulcan orange,indathrene brilliant orange RK, benzidine orange G, indathrene brilliantorange GK, C.I. pigment orange 31, C. I. pigment orange 43.

A red colorant includes, for example, C.I. pigment red 52, C.I. pigmentred 53, C. I. pigment red 19, C.I. pigment red 48:1, C.I. pigment red48:2, C. I. pigment red 48:3, C. I. pigment red 57:1, C. I. pigment red122, C. I. pigment red 150, and C. I. pigment red 184.

A purple colorant includes, for example, C.I. pigment violet 23,manganese purple, fast violet B, and methyl violet lake.

A blue colorant includes, for example, C. I. pigment blue 15, C. I.pigment blue 15:2, C. I. pigment blue 15:3, C.I. pigment blue 15:4, C.I. pigment blue 16, and C. I. pigment blue 60.

A green colorant includes, for example, chromium green, chromium oxide,pigment green B, micalite green lake, final yellow green G, and C. I.pigment green 7.

A white colorant includes compound, for example, zinc powder, titaniumoxide, antimony white, and zinc sulfide.

The colorant may include non-traditional pigments. Examples of suchnon-traditional also referred to as “effect pigments” are: thermochromicpigments, fluorescent pigments, pearlescent pigments, metallic pigments,and combinations thereof. Such “effect pigments” are separate compoundsrelative to the light-scattering pigment.

The colorants can be used each alone or two or more of them of differentcolors can be used together. A plurality of colorants of an identicalcolor system can also be used together. The ratio of the optionalcolorant to the structural polymer 100 is not particularly restrictedand can be properly selected within a wide range in accordance withvarious conditions such as the type of structural polymer 100 or thecharacteristics required for the desired color to be achieved. As anexample, the ratio of the colorant used to the structural polymer 100can be preferably from 0.0001 part by weight or 5 parts by weight orless, and more preferably, 0.0004 parts by weight or more and 5 parts byweight or less based on 100 parts by weight of the structural polymer100.

L* value

On the CIELAB L*, a*, b* color space an L* value of greater than about80 appears bright. In the present invention, the L* value of thecomposition after orientation may be from about: 70, 75, 80, 85, 90, 95,or 97 to 99.5, which is typically the maximum. Prior to orientation ofthe polymethylpentene, the L* value may have a lower range. In preferredembodiments, walls for packages that are white have an L* value greaterthan 80 or greater than 85 or greater than 90 or greater than 95.

Light Barrier

Light barrier is a quality characterizing the prevention of light fromtraveling through a sample over a range of light wavelengths. Lightbarrier can be measured as the average amount of light prevented frompassing through a sample from 400 nm to 700 nm. Light barrier can alsobe measured as optical density. Optical density is −log_(in) of theratio of light passing through a sample. This is beneficial formeasuring samples with very high light barrier. For example, an opticaldensity of 3 means that 99.9% of the light is prevented from passingthrough. In the present invention, the wall may prevent about: 75%, 80%,85%, 90%, 95%, 97%, 98%, 99%, or 99.5% to 100% of the light from passingthrough the wall.

Spectrum of Light Wavelengths

The relevant light spectrum that the disclosed container blocks is notrestricted to the visible light spectrum. Indeed, light within the ultraviolet spectrum and infrared spectrum can cause undesired changes toproducts. In non-limiting examples the spectrum of light wavelengthsblocked by the combination of the structural polymer 100 andpolymethylpentene, the light scattering pigment and/or the colorantincludes: from about 200 nm to about 1200 nm; from about 250 nm to about1000 nm; from about 300 nm to about 900 nm; from about 350 nm to about800 nm; from about 400 nm to about 700 nm; from about 350 nm to about600 nm; and from 350 nm to 550 nm.

Barrier Properties

Packaging may provide other barrier properties to, for example,moisture, oxygen, microbes, grease, or carbon dioxide. Indeed, incertain embodiments, the package wall may include oxygen scavengers.Examples of such oxygen scavengers are: polybutadiene-PET blockcopolymers with transition metal salts used as a catalyst; polyalkyleneglycols, their copolymers, and blends thereof; and copolyetheresters.

Density

Polymethylpentene has a particular advantage of having a low density.Low density reduces overall part weight and leads to cost savings. Forexample, polymethylpentene has a density of 0.83 g/cm³, whereaspolyester terephthalate has a density of 1.39 g/cm³. By incorporating 5parts polymethylpentene with 100 parts polyester terephthalate, forexample, the composite density is reduced by 3.1%. Since many plasticarticles are made to a specific volume, this results in a lower articleweight and less polymer consumption. Light scattering pigments likeTiO₂, BaSO₄, or ZnS have very high density, which when incorporated intoa structural polymer can lead to increased article weight. For example,incorporating 5 parts TiO₂, the composite density increases by 3.2%.Using instead, a combination of 5 parts polymethylpentene and 5 partsTiO₂, the total weight of, for example, a container is equivalent tothat of a PET container.

Packaging Articles

The white, light-blocking compositions disclosed herein can be employedto make packaging articles having various forms. Suitable articlesinclude, but are not limited to, flexible sheet films, flexible bags,pouches, semi-rigid and rigid containers such as bottles (e.g., PETbottles), trays, and containers.

Typical flexible films and bags include those used to package variousfood items and may be made up of one or a multiplicity of layers to formthe overall film or bag-like packaging material. The whitelight-blocking composition of the present invention can be used in one,some or all of the layers of such packaging material.

Typical rigid or semi-rigid articles include plastic, paper or cardboardcontainers, such as those utilized for milk, juices, soft drinks,alcohol as well as thermoformed trays or cups normally having athickness in the range of from about 100 μm to about 1000 μm. The wallsof such articles can comprise single or multiple layers of materials.The articles can also take the form of a bottle or can, or a crown, cap,crown or cap liner, plastisol or gasket. The white light-blockingcomposition of the present invention can be used as an integral layer orportion of, or as an external or internal coating or liner of, theformed semi-rigid or rigid packaging article. As a liner, the whitelight-blocking composition can be extruded as a film along with therigid article itself, in, e.g., a co-extrusion, extrusion coating, orextrusion lamination process, so as to form the liner in situ duringarticle production; or alternatively can be adhered by heat and/orpressure, by adhesive, or by any other suitable method to an outersurface of the article after the article has been produced.

In one non-limiting embodiment a container includes a bottom connectedto a side wall, defining an interior space. The container may be formedof the white light-blocking composition. In such an embodiment, thecontainer may also include a top containing an opening connected to theside wall with optionally a seal for opening. A light sensitive product,for example a food product such as milk, may be placed within theinterior space. The white light-blocking composition may enclose all orpart of the container or be restricted to just the opening. Finally, thecontainer may be oxygen-resistant.

In one non-limiting embodiment of the present invention, the compositionof the present invention, (e.g., a structural polymer base,polymethylpentene, and a light scattering pigment, and optionallyanother pigment and/or a colorant) can be employed to form a monolayerbottle. In another non-limiting embodiment of the present invention, thecomposition of the present invention can form one or more layers of amultilayer bottle.

Besides articles applicable for packaging food and beverage, articlesfor packaging other products can also benefit from the presentinvention. Such products would include pharmaceuticals, light sensitivemedical products, audio/visual film and the like. Product labellingpurposes may also require the package be a bright white color so thatspecific trade dress may be printed on the container.

Article Walls

In some embodiments, the invention concerns use of the compositionsdescribed herein as a component of a wall that is used in a desiredwhite package for light sensitive materials.

The wall may be a rigid one, a flexible sheet, or a clinging film. Itmay be homogenous or a laminate or coated with other polymers. If it islaminated or coated, then the white color and light blocking propertymay reside in a layer of the wall which alone would not performsatisfactorily (e.g., not be bright white enough). However, if the layeris combined with other white layers which block light the article mayperform satisfactorily (e.g., appearing bright white and blockinglight).

The package walls of the instant invention can be a single layer or amultilayer construction. In some embodiments using multilayer walls, theouter and inner layers may be structural layers with one or moreprotective layers containing the structural and polymethylpentene therebetween. In some embodiments, the outer and inner layers comprise apolyolefin, a polyester, or nylon. In certain embodiments, a singlelayer design is preferred. Such a layer may have advantages insimplicity of manufacture and cost.

Method of Manufacture

The instant compositions can be made by mixing a polyester structuralpolymer (PET, for example) with polymethylpentene, a light scatteringpigment, and optionally another pigment and/or colorant. Suchcompositions can be made by any method known to those skilled in theart. In certain embodiments, some or part of the light scatteringpigment and/or colorant may exist in the base structural polymer or inpolymethylpentene prior to mixing. This residual opacifier or colorant,for example, can exist as a result of a reclamation process (i.e.,recycling). In some embodiments, structural polymer, polymethylpentene,light scattering pigment, and optional other pigment and/or colorant aremixed by tumbling in a hopper. Other optional ingredients can be addedduring this mixing process or added to the mixture after theaforementioned mixing or to an individual component prior to theaforementioned mixing step.

The instant composition can also be made by adding each ingredientseparately and mixing the ingredients prior to melt processing thecomposition to form an article. In some embodiments, the mixing can bejust prior to the melt process zone. In other embodiments, one or moreingredients can be premixed in a separate step prior to bringing all ofthe ingredients together.

The instant composition may also be produced by melt kneading. In such anon-limiting embodiment, the polyester structural polymer,polymethylpentene, light scattering pigment and optional colorant (andother components if present) are melt-kneaded to prepare a kneaded resinproduct. The melt kneading is conducted substantially without the use ofan organic solvent, however, small amounts of an organic liquid(including an organic solvent) may be present as a process aid to, forexample, control dusting of the polymer. The kneaded polymer compositionmay optionally contain additives, for example, a releasing agent such aswax and an additive such as a charge controller. The additives arekneaded together with the polyester structural polymer,polymethylpentene, light scattering pigment, and optional colorant anddispersed in the kneaded polymer composition.

In another aspect, the invention provides a package, whether rigid,semi-rigid, collapsible, lidded, or flexible or a combination of these,comprising a wall as formed from the compositions described herein. Suchpackages can be formed by methods well known to those skilled in theart.

Among the techniques that may be used to make articles are moldinggenerally, stretch blow molding, extrusion, thermoforming, extrusionblow molding, biaxial orientation, and (specifically for multilayerstructures) co-extrusion and lamination using adhesive tie layers.Orientation, e.g., by stretch blow molding, of the polymer is especiallyattractive with polyesters because of the known mechanical advantagesthat result.

The melt processing zone for making the article can be operated undercustomary conditions effective for making the intended articles, such aspreforms, bottles, trays, and other articles mentioned below. In oneembodiment, such conditions are effective to process the melt withoutsubstantially increasing the IV of the melt and which are ineffective topromote transesterification reactions. In some preferred embodiments,suitable operating conditions effective to establish a physical blend ofthe structural polymer, polymethylpentene, light scattering pigment andcolorant are temperatures in the melt processing zone within a range ofabout 200° C. to about 300° C. at a total cycle time of less than about6 minutes, and typically without the application of vacuum and under apositive pressure ranging from about 0 psig to about 900 psig. In someembodiments, the residence time of the melt on the screw can range fromabout 1 to about 4 minutes.

Specific articles include preforms, trays, containers, and rigidpackages for the packaging of food, beverages, cosmetics,pharmaceuticals, and personal care products where a bright white packageis desired and light blocking is needed. Examples of beverage containersare bottles for holding beer and juice, and the invention isparticularly useful in bottle applications containing milk or any otherbeverage where the package is desired to be a bright white and lightdetrimentally affects the flavor, fragrance, performance (preventvitamin degradation), or color of the drink. Rigid packages include foodtrays and lids. Examples of food tray applications include dual ovenablefood trays, or cold storage food trays, both in the base container andin the lidding (whether a thermoformed lid or a film), where thefreshness of the food contents can decay when exposed to light. Thecompositions of the instant invention also find use in the manufactureof containers for pharmaceuticals or medical devices.

Master Batch

In another aspect, the instant composition can be used as a master batchfor blending with a polymer or a polymer containing component. In suchcompositions, the concentration of, for example, the polymethylpentene,light scattering pigment, and optionally another pigment and/or acolorant will be higher to allow for the final blended product to havesuitable amounts of these components. The master batch may also containan amount of the polyester structural polymer with which the masterbatch is to be blended. In other embodiments, the master batch maycontain a polyester structural polymer that is compatible with a secondstructural polymer to which the master batch is to be blended. In otherembodiments, the mater batch may contain polymethylpentene and a secondfunctional polymer, one or both of which may be incompatible with thestructural polymer.

Definitions

In this specification and in the claims that follow, reference will bemade to a number of terms, which shall be defined to have the followingmeanings.

As used herein, the terms “a”, “an”, “the” and the like refer to boththe singular and plural unless the context clearly indicates otherwise.“A bottle”, for example, refers to a single bottle or more than onebottle.

Also as used herein, the description of one or more method steps doesnot preclude the presence of additional method steps before or after thecombined recited steps. Additional steps may also be intervening stepsto those described. In addition, it is understood that the lettering ofprocess steps or ingredients is a convenient means for identifyingdiscrete activities or ingredients and the recited lettering can bearranged in any sequence.

Where a range of numbers is presented in the application, it isunderstood that the range includes all integers and fractions thereofbetween the stated range limits. A range of numbers expressly includesnumbers less than the stated endpoints and those in-between the statedrange. A range of from 1-3, for example, includes the integers one, two,and three as well as any fractions that reside between these integers.

As used herein, “master batch” refers to a mixture of polymethylpentene,light scattering pigment, and optional colorant and optional structuralpolymer, and optional other polymer and optional other additives thatwill be diluted, typically with at least additional structural polymer,prior to forming an article. As such, the concentrations ofpolymethylpentene, light scattering pigment and/or colorant are higherthan in the formed article.

The following examples are included to demonstrate preferred embodimentsof the invention regarding the usefulness of PET base resin blended withpolymethylpentene and a light scattering pigment to make bright whitepackages. It should be appreciated by those of skill in the art that thetechniques disclosed in the examples which follow represent techniquesdiscovered by the inventors to function well in the practice of theinvention, and thus can be considered to constitute modes for itspractice. However, those of skill in the art should, in light of thepresent disclosure, appreciate that many changes can be made in thespecific embodiments which are disclosed and still obtain a like orsimilar result without departing from the spirit and scope of theinvention.

EXAMPLES

The following materials are referenced in Table 1 below:

-   -   PMP—polymethylpentene, grade RT-31 from Mitsui Chemicals        America, Inc. Counter

Example 5 and Example 6 used grade was RT-18 from Mitsui ChemicalsAmerica, Inc.

-   -   PET—polyethylene terephthalate, grade PQB-4 from Polyquest, Inc.        0.80 IV bottle grade polymer.    -   PETG—glycol modified co-polyester, grade Skygreen K2012 from SK        Chemicals.    -   TiO₂—titanium dioxide, light scattering pigment, CI Pigment        White 6, grade CR-834 from Tronox Limited, general purpose        rutile grade.    -   PPRO—polypropylene, grade Primaflex® HP 3500 from Plastics        Solutions, Inc. 35 melt flow homopolymer.    -   ZnS—Zinc sulfide, light scattering pigment, CI Pigment White 7,        grade Sachtloth HD-S from Venator.    -   PBlk 7—carbon black, Black Pearls 4350 from Cabot.    -   PBlk 11—Black iron oxide, CI Pigment Black 11, grade Bayferrox        318M from Lanxess.    -   SB 104—CI Solvent Blue 104, non-light scattering colorant, grade        Keyplast Blue KR from Milliken.    -   TiO₂ MB—65% TiO₂ and 35% PET were extruded in a 25 mm corotating        twin screw extruder at 300 RPM and 250° C. and chopped into        pellets.    -   ZnS MB—50% ZnS and 50% PET were extruded in a 25mm corotating        twin screw extruder at 300RPM and 250° C. and chopped into        pellets.    -   SB 104 MB—10% SB 104 and 89.3% PETG, 0.5% epoxidized soybean        oil, and 0.2% BNX 1010 anti-oxidant stabilizer grade were        extruded in a 25 mm corotating twin screw extruder at 300 RPM        and 250° C. and chopped into pellets.

Examples 6, 7a, 7b, 7c, 7d, 8a, 8b, 8c, 9 and 10 all utilized a pre-mademaster batch. The composition of each master batch is listed in Table 1.All master batch compositions were extruded in a 25 mm corotating twinscrew extruder at 300 RPM and chopped into pellets. Each master batchwas added to the feed throat of the extrusion step of a blow moldingprocess at the amount shown in Table 1 below:

TABLE 1 Masterbatch samples used in examples and counter examples PPROPMP TiO₂ ZnS PBlk 7 PBlk 11 PET PETG Dosage Ex 6 MB 50.00% 50.00% 5.00%Ex 7a MB 99.01% 0.99% 6.06% Ex 7b MB 65.00% 0.50% 34.50% 12.00% Ex 7c MB43.10% 56.04% 0.86% 6.96% Ex 7d MB 43.29% 56.28% 0.43% 6.93% Ex 8a MB99.40% 0.60% 10.06% Ex 8b MB 65.00% 1.20% 33.80% 5.00% Ex 8c MB 74.78%24.33% 0.90% 6.68% Ex. 9 MB 25.00% 75.00% 3.00% also Ex 10 Ex. 10 MB0.50% 99.50% 4.00%

For all samples, the additives were mixed at the feed throat of theextrusion step of a blow molding process on a Nissei ASB 50M blowmolding machine. Bottles were blown with an axial orientation of 3.3xand a circumferential orientation of 3.3x for a total wall orientationof 10.9x². The final composition of each sample is shown in Table 2below:

TABLE 2 Final bottle compositions. Name PMP TiO2 PPRO ZnS PBlk 7 PBlk 11SB 104 PET Ex 1a 6.00% 94.00% Ex 1b 7.80% 92.20% Ex 1c 3.00% 3.90%93.10% Ex 1d 2.40% 3.12% 94.48% Ex 2a 10.00% 90.00% Ex 2b 3.25% 96.75%Ex 2c 1.63% 5.00% 93.38% Ex 3 1.50% 0.50% 98.00% Ex 4 1.50% 0.25% 98.25%Ex 5 1.50% 0.60% 97.90% Ex 6 2.50% 2.50% 95.00% Ex 7a 6.00% 0.06% 93.94%Ex 7b 7.80% 0.06% 92.14% Ex 7c 3.00% 3.90% 0.06% 93.04% Ex 7d 3.00%3.90% 0.03% 93.07% Ex 8a 10.00% 0.06% 89.94% Ex 8b 3.25% 0.06% 96.69% Ex8c 1.63% 5.00% 0.06% 93.32% Ex 9 0.750% 2.25% 97.00% Ex 10 0.750% 2.25%0.02% 96.98%

The above referenced compositions were then subjected to orientationforces and their appearance properties were measured. The results of themeasurements are shown in Table 3 below:

TABLE 3 Measured appearance properties Light Gonio- GoniochromaticOptical PMP to Example Barrier appearance Non pearlescent Density L* a*b* Pigment Ex 1a 96.2% 26.8 No 1.24 96.9 0.0 −0.1 N/A Ex 1b 96.3% 3.7Yes 1.25 97.1 −0.7 0.8   0:1 Ex 1c 98.2% 4.0 Yes 1.52 97.7 −0.6 1.10.77:1 Ex 1d 96.7% 4.2 Yes 1.20 97.6 −0.5 0.7 0.77:1 Ex 2a 90.5% 27.8 No0.88 96.1 0.0 0.1 N/A Ex 2b 90.1% 2.5 Yes 0.82 96.2 −0.8 0.8 N/A Ex 2c88.5% 4.9 Yes 0.75 96.2 −0.6 0.7 N/A Ex 3 91.0% 9.7 Yes 0.80 97.2 −0.30.1   3:1 Ex 4 90.6% 15.1 No 0.79 96.4 −0.4 0.3 6.07:1 Ex 5 99.9% 32.0No 3.47 50.9 −7.2 −36.5 1.25:1 Ex 6 96.5% 5.9 Yes 1.17 97.1 −0.4 0.4  1:1 Ex 7a 100.0% 29.9 No 3.44 85.7 0.5 1.2  100:1 Ex 7b 99.7% 4.5 Yes2.95 87.2 −0.8 −1.6   0:1 Ex 7c 100.0% 5.4 Yes 5.93 86.6 −0.2 −0.50.76:1 Ex 7d 99.9% 4.6 Yes 3.00 91.3 −0.1 0.5 0.76:1 Ex 8a 98.6% 29.3 No1.73 83.9 0.6 0.7 N/A Ex 8b 99.0% 4.0 Yes 2.08 81.6 −0.8 −2.1 N/A Ex 8c99.2% 7.2 Yes 2.07 80.9 0.2 −0.3 N/A Ex 9 91.5% 2.9 Yes 1.13 96.1 0.2−0.3   1:3 Ex 10 100.0% 5.9 Yes 3.80 69.0 −0.5 −1.6   1:3

Examples 1a, 1b, 1c, 1d

Ex 1a, 1b, 1c, and 1d show that there is synergy when an orientedpackage wall combines PMP and a light scattering pigment. Ex 1a, usingjust PMP has a gonioapparent appearance and light barrier of 96.2%. Ex1b, using just a light scattering pigment, requires a very high level ofmasterbatch to achieve the same light barrier of 96.3%. By using half ofthe light barrier contribution from Ex 1a and Ex 1b, one skilled in theart would anticipate the same light barrier performance. However, Ex 1cshows that the light barrier is improved while maintaining agoniochromatic appearance. Ex 1d further illustrated the synergy byreducing the total amount of both PMP and the light scattering pigmentby 20% while still matching the light barrier of Ex 1a and Ex 1b andmaintaining a goniochromatic appearance.

Counter Examples 2a, 2b, 2c

Ex 2a, Ex 2b, and Ex 2c show that there is no synergy when an orientedpackage wall combines a different olefin polymer and a light scatteringpigment. Ex 2a, using PPRO, requires a very high loading level and stillcannot achieve light barrier similar to Ex 1. Ex 2b, using just a lightscattering pigment, matched the light barrier of Ex 2a. By using half ofthe light barrier contribution from Ex 1a and Ex 1b, one skilled in theart would anticipate the same light barrier performance. However, Ex 2cshows the light barrier is slightly worse than Ex 2a and Ex 2b.

Example 3 and Counter Example 4

Example 3 and Counterexample 4 show that at a ratio of PMP to lightscattering pigment of about 3:1 results in an appearance that isgoniochromatic and maintains color across a range of viewing angles.However, increasing that PMP to light scattering pigment up to about 6:1results in an appearance that is gonioapparent and no longer maintainscolor across a range of viewing angles.

Counter Example 5

Counter Example 5 shows that using a non-light scattering pigment, doesnot provide a goniochromatic appearance. The added colorant must be alight scattering pigment, not an absorbing dye.

Example 6

Example 6 shows that other light scattering pigments can be used, in thecase of Ex 6, CI Pigment white 7, zinc sulfide.

Examples 7a through 7d

Ex 7a, 7b, and 7c show Ex 7a, 7b and 7c use the same structural polymer,PMP and light scattering pigment as Ex 1a, Ex 1b, and Ex 1c but with theaddition of 0.060% PB1k 11 in the final composition. Because the lightbarrier is so high, the synergy in light barrier is measured usingoptical density. Ex 7d shows that, due to the synergy between PMP andTiO₂, the same light barrier can be achieved but with a reduced amountof PB1k 11, yielding a higher L* and brighter white while maintaining agoniochromatic appearance.

Counter Examples 8a through 8c

Ex 8a, Ex 8b, and Ex 8c use the same structural polymer, PPRO, and lightscattering pigment as Ex 2a, Ex 2b and Ex 2c but with the addition of0.060% PB1k 11 in the final composition. Since there is no synergybetween PPRO and TiO2, the L* appearance of Ex 7c is lower than Ex 8aand of Ex 8b.

Examples 9 and 10

Ex 9 and 10 show that there is synergy when an oriented package wallcombines PMP and a light scattering pigment. Ex 9, using PMP and TiO2has a gonioapparent appearance and light barrier of 91.5%. Ex 10, usesPMP, TiO₂, and carbon black (PB1k 7) and also has a gonioapparentappearance and blocks all light.

Although illustrated and described above with reference to certainspecific embodiments the present invention is nevertheless not intendedto be limited to the details shown. Rather, various modifications may bemade in the details within the scope and range of equivalents of theclaims and without departing from the spirit of the invention. It isexpressly intended, for example, that all ranges broadly recited in thisdocument include within their scope all narrower ranges which fallwithin the broader ranges. It is also expressly intended that the stepsof the methods of using the various compositions disclosed above are notrestricted to any particular order.

1-20. (canceled)
 21. A packaging article comprising a wall, wherein thewall comprises: a polyester; about 0.2 to about 4.0 weight percentpolymethylpentene (PMP); and about 0.1 to about 5.0 weight percent lightscattering pigment, wherein the ratio of PMP to light scattering pigmentin the layer is from about 5:1 to about 1:5, and wherein the wall isgoniochromatic.
 22. The packaging article of claim 21, wherein the wallhas a gonioappearance of less than 10 units, measured as DE_(CMC) with a45° incident light source between 15° near-specular reflection and 110°far specular reflection.
 23. The packaging article of claim 21, whereinthe polyester is selected from polyethylene terephthalate (PET),polybutylene terephthalate (PBT), polylactic acid (PLA), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN),polyethlene furanoate (PEF), polycyclohexylene dimethylene terephthalate(PCT), sulfonated polyesters, polycaprolactone (PCL),polyhydroxyalkanoate (PHA), and copolymers and combinations thereof. 24.The packaging article of claim 21, wherein the polyester is PET.
 25. Thepackaging article of claim 21, wherein the light scattering pigment isselected from titanium dioxide (TiO₂), metal oxide particles, bariumsulfate (BaSO₄), and zinc sulfide (ZnS).
 26. The packaging article ofclaim 25, wherein the light scattering pigment is titanium dioxide(TiO₂).
 27. The packaging article of claim 21, wherein the wall has alight barrier, for light with wavelengths ranging from about 400 nm toabout 700 nm, of greater than about 90%.
 28. The packaging article ofclaim 21, wherein the wall has an L* value according to CIELAB colorspace of greater than about
 75. 29. The packaging article of claim 21,wherein the wall is a mono-layer container wall.
 30. The packagingarticle of claim 21, wherein the wall is an outer wall of the packagingarticle.
 31. The packaging article of claim 21, wherein the layerfurther comprises a second pigment or colorant.
 32. The packagingarticle of claim 31, wherein the second pigment or colorant comprises adye, a thermochromic pigment, a fluorescent pigment, a pearlescentpigment, a metallic pigment, or a combination thereof.
 33. The packagingarticle of claim 21, wherein the polyester comprises polyethyleneterephthalate (PET), the wall has an L*-value, according to the CIELABcolor scale, of greater than 75, and the wall has a light barrier, forlight with wavelengths ranging from 400 nm to 700 nm, of greater than 90percent.
 34. The packaging article of claim 21, wherein the polyester ispolyethylene terephthalate (PET), the PMP in the layer is present in anamount of about 0.2 to about 3.0 weight percent, the light scatteringpigment in the layer is titanium dioxide present in an amount of about0.2 to about 4.0 weight percent, and the ratio of PMP to titaniumdioxide in the layer is about 3:1 to about 1:3.
 35. The packagingarticle of claim 34, wherein the wall has an L*-value, according to theCIELAB color space, of greater than 80, and the wall has a lightbarrier, for light with wavelengths ranging from 400 nm to 700 nm, ofgreater than 98%.
 36. The packaging article of claim 21, furthercomprising a bottom connected to the wall, wherein the bottom and thewall at least partially define an interior space.
 37. A method ofproducing a wall of a packaging article, the method comprising:obtaining a composition comprising a mixture of a polyester,polymethylpentene (PMP), and a light scattering pigment, wherein the PMPcomprises about 0.2 to about 4.0 weight percent of the mixture, thelight scattering pigment comprises about 0.1 to about 5.0 weight percentof the mixture, and the ratio of PMP to light scattering pigment in themixture is about 5:1 to about 1:5; and subjecting the composition to anorientation stress to produce the wall of the packaging article, whereinthe wall is goniochromatic.
 38. The method of claim 37, wherein thedensity of the composition prior to being subjected to the orientationstress is equal to or lower than the density of the polyester.
 39. Themethod of claim 37, wherein the density of the wall after beingsubjected to the orientation stress is equal to or lower than thedensity of the polyester.
 40. The method of claim 37, wherein theorientation stress is selected from: blow molding, uniaxial or biaxialsheet orientation, thermoforming, and fiber spinning.